Currently, a submerged biological filtering matrix for a closed, circulated water filtering system must be physically cleaned by backflushing, scrubbing, drainage, or even periodic replacement. The build-up of biological material, the inclusion of suspended solids, and capture of uneaten feed characteristically clogs submerged filtering matrix materials. The need to continually clean these submerged matrices paradoxically requires one to select materials with large pore sizes and less surface area per unit volume.
The use of submerged biological filtration systems for the bioremediation of waste products or improvement in water quality has been discouraged by the subsequent clogging and inactivation of the surfaces as biofloc and other solids accumulate. As the pore space decreases, channelization occurs within the filtering matrix generating additional anaerobic areas that decrease the efficiency of the biological filter. Removal of these materials has proven to be expensive and technologically challenging.
Current recommendations on bioremediation systems use more energy-intensive technologies such as rotating biological contactors or trickle towers to maintain aerobic, fixed-film surfaces for waste bioremediation. The invention herein provides a means for minimizing maintenance and potential clogging of a submerged filtering matrix that saves time and energy. Additionally, the invention herein increases the bioremediation efficiency of existing technologies.
Prior U.S. patents that use small animals in aquatic purification processes include U.S. Pat. No. 4,086,161 of Burton entitled "Ecological System & Method" and U.S. Pat. No. 4,995,980 by Jaubert entitled "System for Biological Purification of Water Containing Organic Materials & Derivative Products." Both of these references use small animals as part of the water purification process in either wetlands of an open aquatic system or in aquaria of a closed aquatic system. In particular Burton '161 calls for use of a crustacean, e.g. Daphnia, an aerobic scavenger that can purify wetland waters on bark floats. In closed recirculated water systems, Jaubert '980 teaches of a natural filtering system for aquaria that use small burrowing detritus eating animals that are incorporated with a porous filtering medium. Neither of these references teach or suggest the use of amphipods in water purification methods with attendant apparatus that ensures self-sustaining maintenance free operation of their respective aquatic systems.
Other prior U.S. patents that use amphipods for bioassay environmental applications includes U.S. Pat. No. 5,194,147 by Augustine et al. entitled "Decontamination System" and U.S. Pat. No. 5,194,634 by Bradley entitled "Bioassay for Environmental Quality". Neither of these patents teach or suggest using amphipods for water purification applications.